The left is back — and millennials are leading the way. “Socialism” was the most searched word on the Merriam-Webster website in 2015, and a 2016 poll showed that 43 percent of Iowa Democrats described themselves as “socialists.” Despite the setback of President Trump’s electoral victory, the left continues to grow. Publications like the magazine Jacobin, launched by millennial Bhaskar Sunkara, now reach more than 1 million website visitors each month.

But the millennial left is not a return to the New Left of the 1960s — the student radicals, hippies and Yippies who raised hell in their efforts to end the Vietnam War and change American culture to make it less racist and sexist and more authentic. Rather it invokes the ideas of the Old Left of the 1930s — the militant labor unions, socialists and even communists who, in the context of the worst economic depression in American history, sought a genuine alternative to capitalism.

The Old Left of the 1930s grew out of a 19th-century socialist movement and focused its political energy on the problems of capitalism. It was also deeply critical of Franklin D. Roosevelt’s brand of liberalism. Although Roosevelt championed the “common man” and pushed through New Deal reforms that became the bedrock of 20th-century American social democracy, the 1930s left criticized FDR and liberals for the compromises they made with capitalism.